1. Field of the Invention
The invention relates to the slitting of sheet material. More particularly, the invention relates to the slitting of sheet metal, such as amorphous metal sheet.
2. Brief Description of the Prior Art
Conventional rotary slitting devices, such as those manufactured by Technical AG, Grenchen, Switzerland, have employed rotary knives mounted on arbor shafts and separated by discrete spacer rings.
Other conventional rotary slitting devices employ thin, flexible rotary knives rigidly located at regularly spaced positions along a top and a bottom arbor shaft. The arbor shafts are parallel, and the top and bottom knives overlap in alternating, intermeshing fashion. The arbor shafts are also slightly offset sideways in the axial direction to bring the intermeshing top and bottom knife faces into contact with one another. The contacting knives deflect slightly and the resulting spring action holds the knives in close contact during use.
Another type of slitting device employs a gang of regularly spaced rotary knives held at fixed axial positions along a shaft. The knives engage a rotary anvil which has the general configuration of a circumferentially grooved cylinder. The flexible knives are positioned within the grooves and offset sideways to bring a side of each knife into contact with a side of its corresponding groove. The knife deflects slightly to provide a spring action that maintains contact between the knife and the side of the groove during operation.
Still another type of slitting device, such as manufactured by Arrow Converting Equipment, Inc. located in Fairfield, N.J., employs a thin, rotary, male knife blade which engages an annular groove formed into one axial face of a female knife element. A relatively bulky knife holder portion carries the male blade, and an annular knife key "garter" spring urges the blade axially against an annular retaining ring. However, when employed to slit thin metal, this type of device produces undesired width variations and folds and tears on the slit edges.
Conventional slitting devices, such as those discussed above, have been expensive or have not been satisfactory for slitting thin metal sheet, such as amorphous, glassy metal strips. When slitting metal, the devices have employed expensive, precisely machined spacers placed between individual knife elements to maintain precise clearances between the knives. These clearances must be precisely maintained to produce consistent evenly slit edges. If the gap clearance between intermeshing is too small or too large, the slit edges are uneven, bent or have undesired burrs. Machine setup time is long and costly because these clearances must be precisely measured and established. In addition, normal operation rapidly degrades the clearances. For example, thermal expansion can undesirably increase or decrease the clearance gap between the cutter knives.
Slitting devices with flexible, intermeshing knives that actually contact one another have been suitable only for slitting soft sheet material, such as plastic or mylar. The flexible knife slitting devices are expensive to manufacture and expensive to maintain because the individual knife elements must be very precisely aligned along their respective arbor shafts. If a knife element is mispositioned, it will not contact its corresponding, adjacent knife element mounted on the opposite arbor with the correct amount of side force, and the slitting operation will be degraded.
Thus, conventional slitting devices for thin sheet metal have been expensive, difficult to set up and have required precision machined components.